﻿<html>
<head>
<script type="text/javascript">
function checkArea(x){
    var other_area = document.getElementById( "other_area" );
    if(x.value == "other"){
        other_area.style.display = "inline";
    } else {
        other_area.style.display = "none";
    }
}
</script>
</head>
<body>
<form>
<p>
请选择所在地区：<select name="area" onchange="checkArea(this);">
<option value="bj"> 北京 </option>
<option value="tj"> 天津 </option>
<option value="sh"> 上海 </option>
<option value="other"> 其他 </option>
</select>
</p>
<p id="other_area" style="display:none;">
请填写地区：<input type="text" onchange="alert('已经修改了值')"/>
</p>


</form>
</body>
</html>
